Arose from my bed this morning with new determination. Followed the steps in the guide above. I've got into a loop though. I delete them with pluma, when I 'aptitude install' them the following occurs:

Now that guide says to repeat the steps until it's fixed, but I've done it three times now and I'm just going round in circles. Will I have to reinstall my whole system? If so, is there a way to create a USB stick with Liquorix already on it and all updated with packages at the latest version?

unfortunately there's no way to do at you want/need (unless you respin your own live-dvd with the updated packages included; for that the easiest howto i know is this http://community.linuxmint.com/tutorial/view/918 usually is used <and that was Clem's intention> to strip down the installation disk so that it can fit in a cd, but i believe that it can be used to do what you want >> tho i never tried it)

a new iso including all the up6 updates should be released this month anyway.